1. Field of the Invention.
The present invention relates to devices for raising, lowering and/or leveling a camper body. More particularly, the present invention relates to a novel camper jack that is implemented so as to present a reduced and streamlined profile for improved safety and visibility when the jack is mounted to a camper body, while at the same time providing a jack that is efficient and economical.
2. Prior State of the Art
Camper jacks are commonly used to raise, lower and support camper bodies and are especially prevalent with those types of camper bodies which rest in the bed of a pick-up truck. Typically, jacks of this type have an outer housing portion which is permanently mounted at each corner of the camper body. Disposed within the housing is a leg portion, which can be extended or retracted in a telescoping fashion by operating the jack's lifting mechanism. Thus, when the camper body is to be removed from the truck, each of jack legs are extended to the ground, and then further advanced so as to lift the camper body from the bed of the truck. The truck can then be driven out from beneath the camper. When the camper is to be mounted to the truck bed, the process is reversed.
There are currently available a wide variety of camper jack implementations, but generally camper jacks are based on either of a hydraulic or a mechanical design. Hydraulic jacks are generally easy to operate and are capable of lifting and supporting heavy loads. However, some hydraulic jacks are also subject to a several undesirable drawbacks. Because a hydraulic system is utilized to generate the lifting force of the jack, some hydraulic jacks are susceptible to seal failure and fluid leakage--conditions which can cause decreased jack performance and/or failure. Further, as is well known, certain hydraulic jacks must be secured, or locked in place when a load is being supported, so as to prevent the load from swaying or drifting to the ground over time. Consequently, these hydraulic jacks may not be suitable for long-term support/storage of a camper body. Hydraulic systems can also be negatively affected by extreme temperatures, and thus some hydraulic jacks may not operate satisfactorily under certain cold or warm weather conditions. Finally, the components used in a hydraulic system are expensive, which results in a relatively expensive camper jack.
Some of the problems inherent in some hydraulic systems have been addressed by designing camper jacks which use only mechanical components. Typically, a jack of the mechanical variety generates a lifting force by way of screw and nut mechanism. Actuation of the leg jack is effected by turning a hand crank, which acts through a gearing assembly to rotate a lead screw. This lead screw is threaded through a nut, typically constructed of steel, brass or bronze, which is non-rotatably attached to the jack leg. When the lead screw is rotated, the nut travels upwardly or downwardly along the screw, thereby causing the jack leg to be retracted or extended.
Mechanical jacks of this type are not without drawbacks either. A metal screw and steel nut arrangement is slower and less efficient and thus more difficult to operate than is a hydraulic system for raising and lowering heavy loads. In order to more closely approximate the efficient and smooth lifting characteristics of the hydraulic jack, mechanical screw jacks have been designed to utilize a sophisticated--and therefore expensive--ball screw technology, wherein a ball screw is threaded through a ball nut. As is well known, the ball nut contains a train of ball bearings which, when the ball screw is rotated, circulate within the nut and around the screw so as to reduce the friction between the two. This arrangement approximates the efficiency and ease of use found in a hydraulic jack. But, because of the complexity and number of parts required for the ball screw arrangement, a ball screw jack is usually significantly more expensive than a mechanical jack using a standard metal screw and nut arrangement.
Hydraulic and mechanical jacks that are currently available also suffer from a common drawback. As discussed, camper jacks are usually mounted permanently to the camper body. Operation of the jack is usually accomplished by manual operation of a hand crank or pump attachment. These hand operable attachments are either permanently attached to the jack, or are detachably mounted to the jack itself via an external mounting assembly, such as a socket housing, which is in turn is operatively coupled to the internal gear or hydraulic portion of the jack. In either scenario, the hand operable attachment itself, or the external mounting assembly for detachably receiving such an attachment, is not flush with the exterior surface of the jack housing. Instead, the attachment and/or the mounting assembly protrudes out from the camper jack housing. This characteristic can be quite hazardous.
For instance, camper jacks of this type can hinder the driver's view--as for instance through a rear-view mirror--when the camper is mounted to the truck bed. Also, the driver must be cognizant of the additional width of the camper body caused by the camper jack, and the potential for accidental collision is increased--especially when maneuvering in tight spaces.
Camper jacks having attachments or attachment housings that protrude from the jack housing can be especially hazardous to pedestrians or bicyclists, who can be inadvertently struck by the protrusion. The problem is exacerbated by the fact that the camper jack is usually at head level, which increases the risk of serious injury, and by the fact that the protruding part is often difficult to see and avoid. Further, the hazard is present both when the camper body is stationary, as for instance in a crowded campground or along a busy road, and when the camper body is mobile, as for instance along narrow, crowded streets. This problem is of heightened concern in areas where streets are extremely narrow and there are a large number of pedestrians, bicyclists and/or other motor vehicles, such as may be found in many European and Asian countries.
Therefore, there is a need for a camper jack that not only is efficient, easy to use and low in cost, but which does not utilize attachments or attachment housings that extend out from the jack when mounted to the camper body. The present invention addresses this need.